This invention relates to a method and apparatus for testing the strength of rocks and, more particularly, to simulate the action of cutting bits of a mining machine for developing design criteria.
Many tests have been developed for determining the hardness and other characteristics of rock. Devices such as the one shown in U.S. Pat. No. 3,732,725, where an impact gun is used, have been developed for testing compressive strength of materials. Other devices, such as the one shown in U.S. Pat. No. 3,618,369, where a rock specimen is stressed until deformation occurs, have been used to measure the amount of permanent deformation along with the static force necessary to effect the deformation for developing a "penetration index" to use in conjunction with rotary rock cutters on a tunneling machine. Other types of devices are shown in U.S. Pat. Nos. 2,620,386 and 3,056,952, where the hardness of earth strata is tested in conjunction with mining machines.
However, there is no known method or device which has been developed which simulates the action of the cutting bits of a mining machine to determine optimum spacing between adjacent bits, the most efficient sequence in which multiple bits should strike the surface to be mined, the preferred angle of attack and optimum torque of the cutting head. These characteristics should be known so that a continuous mining machine can be designed for maximum performance.